Vibration-actuated micro mirror device

ABSTRACT

The present invention provides a vibration-actuated micro mirror device comprising a substrate having a swinging frame and a reflection mirror, and a vibration part having a first and a second vibration structures coupled to the substrate, wherein the first vibration structure is driven to generate a first complex wave formed by a first and a second wave signals while the second vibration structure is driven to generate a second complex wave formed by a third and a fourth wave signals, and the first and the third wave signals are formed with the same frequency and phase while the second and the fourth wave signals are formed with the same frequency but opposite phases. The first and the second complex waves actuate the substrate such that the swinging frame is rotated about a first axis while the reflection mirror is rotated about a second axis.

CROSS REFERENCE TO RELATED PATENT APPLICATION

This application is a divisional of an application Ser. No. 12/963,024,filed on Dec. 8, 2010.

TECHNICAL FIELD

The present disclosure relates to a micro mirror technology, and moreparticularly, to a vibration-actuated micro mirror device utilizing acomplex wave to actuate a reflection mirror for performing atwo-dimensional rotation movement.

TECHNICAL BACKGROUND

With rapidly increasing demand for micro projectors, there are more andmore manufacturers that are directing their resources and funding towardthe related researches in order to establishing a leading position inthis promising and profitable technology. It is noted that microprojectors can be integrated into all kinds of electronic devices, suchas cellular phones and notebook computers. By a modularization design ofmicro projector, any cellular phone can be equipped with a projectormodule and thus can be used in briefing easily and conveniently that iscomparatively much more capable of attracting consumer interest thanthose without. Most micro projectors that are currently available on themarket are flat in appearance, and consequently, all the components usedin micro projectors are designed solely for reducing the thickness ofthe micro projectors, by that not only the flat and thin microprojectors can be portable, but also can be easily integrated with otherproducts.

One of the key issues for producing a good micro projector is to have arefection mirror that can be driven to rotate within a large angularrange and at high rotation frequency. For a XGA projector displaying aresolution of 800 pixels by 600 pixels to achieve 30 frames per second,its fast axis must be capable operating at 18 kHz or higher, and thefaster the better. Conventionally, there are three different methods foractuating reflection mirrors in micro projectors, which are anelectromagnetic-actuated method, an electrostatic-actuated method and apiezoelectric-actuated method, and accordingly, the reflection mirrorshould be configured differently in corresponding to the way it is beingactuated.

In U.S. Pat. No. 7,442,918, a micro-electro-mechanical system (MEMS)device is disclosed, which utilizes a MEMS process for electroplatingdouble layer planar coils simultaneously on its mirror and out ringrelating respectively to the fast scan axis and the slow scan axis so asto enable the fast and the slow scan axes to be actuated by the Lorentzforce induced from the interaction between the coils and the permanentmagnets disposed at two opposite sides thereof as soon as the coils arecharged. Moreover, in U.S. Pat. No. 7,659,918, a single-axis scanningdevice is disclosed, in which a reflection mirror that is disposed inthe middle of the device is actuated to pivotally oscillate or rotate bythe use of a piezoelectric material, or by the vibration inducedsurrounding the reflection mirror. In addition, there is anothersingle-axis scanning device disclosed in U.S. Pat. No. 7,446,919, inthat there are four piezoelectric elements being used for actuating areflection mirror to rotate as the reflection mirror is disposed in themiddle of the device.

TECHNICAL SUMMARY

The present disclosure related to a high-frequency vibration-actuatedmicro mirror device with ultra-thin and low-power design, which utilizestwo complex electric signals, each composed of signals of two differentfrequencies, to actuate two vibration structures in respective. Thereby,the two vibration structures, being actuated by the two complex electricsignals, are enabled to generate respectively two complex waves ofdifferent wave signals that are to be transmitted to a substrateconfigured with a fast-axis mirror and a slow-axis mirror for enablingthe a swinging frame and a reflection mirror to resonant and thus torotate accordingly. Since the pivotally oscillating of the slow-axismirror can be induced by low-frequency wave signals while the pivotallyoscillating of the fast-axis mirror can be induced by high-frequencywave signals, a two-dimensional scanning operation can be achieved bythe swinging frame and reflection mirror that are being actuated torotate and thus a specific projection effect can be achieved.

In an exemplary embodiment, the present disclosure provides avibration-actuated micro mirror device, comprising: a substrateconfigured with a swinging frame and a reflection mirror; and avibration part, configured with a fixing plate, a first vibrationstructure and a second vibration structure in a manner that the firstand the second vibration structures are disposed respectively on thefixing plate while being coupled to the substrate; wherein, the firstvibration structure has ability to receive a first driving signal so asto generate a first complex wave formed by a first wave signal and asecond wave signal; and the second vibration structure has ability toreceive a second driving signal to generate a second complex wave formedby a third wave signal and a fourth wave signal; wherein, the first wavesignal and the third wave signal are formed with a same first frequencywhile the second wave signal and the fourth wave signal are formed witha same second frequency, and the first and the second complex wavesactuate the substrate for enabling the swinging frame to rotate about afirst axis while enabling the reflection mirror to rotate about a secondaxis.

In another exemplary embodiment, the present disclosure provides avibration-actuated micro mirror device, comprising: a substrate,configured with a swinging frame and a reflection mirror while beingformed with a slot; and a vibration part, configured with a firstvibration structure and a second vibration structure in a manner thatthe first and the second vibration structures are disposed on thesubstrate respectively at two sides of the slot; wherein, the firstvibration structure has ability to receive a first driving signal so asto generate a first complex wave formed by a first wave signal and asecond wave signal; and the second vibration structure has ability toreceive a second driving signal to generate a second complex wave formedby a third wave signal and a fourth wave signal; wherein, the first wavesignal and the third wave signal are formed with a same first frequencywhile the second wave signal and the fourth wave signal are formed witha same second frequency, and the first and the second complex wavesactuate the substrate for enabling the swinging frame to rotate about afirst axis while enabling the reflection mirror to rotate about a secondaxis.

Further scope of applicability of the present application will becomemore apparent from the detailed description given hereinafter. However,it should be understood that the detailed description and specificexamples, while indicating exemplary embodiments of the disclosure, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the disclosure will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description given herein below and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present disclosure and wherein:

FIG. 1 is a schematic diagram showing a vibration-actuated micro mirrordevice according to a first embodiment of the present disclosure.

FIG. 2A is a schematic diagram showing the configurations of the pivotaxes for the swinging frame and the reflection mirror according toanother embodiment of the present disclosure.

FIG. 2B is a schematic diagram showing that the pivot axis of thereflection mirror is disposed a specific distance away from part fromthe center of the reflection mirror according to further anotherembodiment of the present disclosure.

FIG. 3A is a schematic diagram showing a first slot formed on thesubstrate according to an embodiment of the present disclosure.

FIG. 3B is a three-dimensional view of a fixing plate used in thepresent disclosure.

FIG. 4A and FIG. 4B are schematic diagrams showing respectively twovibration-actuated micro mirror devices according to a second embodimentand a third embodiment of the present disclosure.

FIG. 5A is a schematic diagram showing two complex electric signalsbeing received respectively by the first and the second vibrationstructures according to an embodiment of the present disclosure.

FIG. 5B a schematic diagram showing two complex electric signals beingreceived respectively by the first and the second vibration structuresaccording to another embodiment of the present disclosure.

FIG. 6A and FIG. 6B are schematic diagrams showing respectively how theswinging frame and the reflection mirror are being driven to rotate.

FIG. 7A and FIG. 7B is a schematic diagram showing a vibration-actuatedmicro mirror device according to a fourth embodiment of the presentdisclosure.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

For your esteemed members of reviewing committee to further understandand recognize the fulfilled functions and structural characteristics ofthe disclosure, several exemplary embodiments cooperating with detaileddescription are presented as the follows.

Please refer to FIG. 1, which is a schematic diagram showing avibration-actuated micro mirror device according to a first embodimentof the present disclosure. In this embodiment, a vibration-actuatedmicro mirror device 2 includes a substrate 20 and a vibration part 21,in which the substrate 20 is formed with a first opening 200 to be usedfor receiving a swinging frame 201. As shown in FIG. 1, the swingingframe 201 has a first axis 202, being a shaft formed on the swingingframe 201 while protruding out from two opposite sides of the swingingframe 201 by two first ends, which is connected to two opposite innersides of the first opening 200 by the two first ends. Moreover, theswinging frame 201 is similarly formed with a second opening 203 to beused for receiving a reflection mirror 204, and also the reflectionmirror 204 has a second axis 205, being a shaft formed on the reflectionmirror 204 while protruding out from two opposite sides of thereflection mirror 204 by two second ends, that is connected to twoopposite inner sides of the second opening 203 by the two second ends.In this embodiment, the first axis 202 is aligned in a X-axis directionand the second axis 205 is aligned in a Y-axis direction that aredefined in an XYZ Cartesian coordinate system of FIG. 1.

In another embodiment that is shown in FIG. 2A, the first axis 202 ofthe swinging frame 201 is aligned in a Y-axis direction and the secondaxis 205 of the reflection mirror 204 is aligned in a Y-axis directionthat are defined in an XYZ Cartesian coordinate system of FIG. 2A. It isnoted that in the embodiments shown in FIG. 1 and FIG. 2A, the secondaxis 205 is aligned passing through the center of the reflection mirror204. However, in the embodiment shown in FIG. 12B, the second axis 205is aligned a distance d away from the center of the reflection mirror204. In FIG. 1, the substrate 20 is further being formed with a firstslot 206 at a side of the substrate opposite to the first opening 200that is disposed dividing the substrate 20 into a first area 207 and asecond area 208. It is noted that the first slot 206 can be formedpenetrating the substrate 20 in a vertical direction, i.e. in Z-axisdirection, or may be a groove without penetrating the substrate 20.Moreover, as shown in FIG. 3A, the first slot 206 can be composed of asub-slot 2060 that is formed penetrating the substrate 20, and asub-groove 2061 that is not penetrating the substrate 20. It is notedthat the first slot 206, as the one shown in FIG. 1, is not an essentialcomponent for the present disclosure that is can be formed selectivelyat will according to the material of the substrate 20. Nevertheless, theformation of the first slot 206 is to facilitate the energy of thevibration part 21 to be transmitted to the swinging frame 201 and thereflection mirror 204 for driving the two to rotate accordingly.

As shown in FIG. 1, the vibration part 21 comprises a fixing plate 210,a first vibration structure 211 and a second vibration structure 212, inwhich the first and the second vibration structures 211, 212 arerespectively coupled to the fixing plate 210 by an end thereof, whileenabling another ends of the first and the second vibration structures211, 212 to be coupled to the substrate 20 through the fixing plate 210.Moreover, the first and the second vibration structures 211, 212 arecoupled respectively to the first area 207 and the second area 208 thatare divided and formed at two opposite sides of the slot 206. In thisembodiment, the first and the second vibration structures 211, 212 aremade of a piezoelectric material, so that the first and the secondvibration structures 211, 212 can be driven to vibrate by the receivingof electric signals. Please refer to FIG. 3B, which is athree-dimensional view of a fixing plate used in the present disclosure.In this embodiment, for enhancing the vibration of the first and thesecond vibration structures 211, 212, the fixing plate 210 is furtherbeing formed with a second slot 213, by that the first and the secondvibration structures 211, 212 are arranged to be disposed respectivelyat two opposite sides of the second slot 213. It is noted that thesecond slot 213 is not an essential component for the present disclosurethat is can be formed selectively at will with respect to the materialof the fixing plate 21.

Please refer to FIG. 4A and FIG. 4B, which are schematic diagramsshowing respectively two vibration-actuated micro mirror devicesaccording to a second embodiment and a third embodiment of the presentdisclosure. The embodiment shown in FIG. 4A is basically the same as theone shown in FIG. 1, but is different in that: the first and the secondvibration structures 211, 212 in the second embodiment are coupleddirectly to the substrate 20 while enabling a side surface 214 of thefixing plate 210 to abut against a side surface 209 of the substrate 20.Moreover, the embodiment shown in FIG. 4B is basically the same as theone shown in FIG. 1, but is different in that: the first and the secondvibration structures 211, 212 are coupled to the substrate 20 directlywhile enabling a side surface 214 of the fixing plate 210 to be spacedfrom a side surface 209 of the substrate 20 by a gap 215. It is notedthat although there is no such second slot 103 being formed on thesubstrates 20 in FIG. 4A and FIG. 4B as the one shown in FIG. 1, thesecond slot 213 can still be formed in the embodiments of FIG. 4A andFIG. 4B as required in a manner known to those skilled in the art. Inaddition, the same as the fixing plate 210 shown in FIG. 3B, the twodivided areas of the fixing plate 210, that are disposed at two oppositesides of the second slot 213, can further be concaved before mountingthe first and the second vibration structures 211, 212 respectivelythere on at positions corresponding to the concaved areas of the fixingplate 210.

The following description relates to how the first and the secondvibration structures are to be driven to vibrate in the presentdisclosure. In the present disclosure, the first and the secondvibration structures are designed to receive two driving signals inrespectively, in which the driving signal for the first vibrationstructure is a complex electric signal combining a high-frequencyelectric signal and a low-frequency signal that is generated from afrequency synthesizer, and similarly, the driving signal for the secondvibration structure is another complex electric signal combining ahigh-frequency electric signal and a low-frequency signal that isgenerated from a frequency synthesizer. Please refer to FIG. 5A, whichis a schematic diagram showing two complex electric signals beingreceived respectively by the first and the second vibration structuresaccording to an embodiment of the present disclosure. As shown in FIG.5A, the complex electric signal 90 is used for driving the firstvibration structure 211, while the complex electric signal 91 is usedfor driving the second vibration structure 212. It is noted that thehigh-frequency signals in the complex electric signals 90, and 91 are ofthe same phase, but the phases of the low-frequency signals in thecomplex electric signals 90, and 91 are opposite to each other.Moreover, the first and the second vibration structures 211, and 212 areconfigured to share a same grounding electrode 22, by that the amount ofsignal lines required can be reduced. The signal lines 23, and 24 aredefined to be signal input where the complex electric signals 90, and 91are fed respectively to the first and the second vibration structures211, and 212 for driving the two to vibrate accordingly. It is notedthat the term “high-frequency” used in the present embodiment iscomparative to the term “low-frequency”, so that they can be determinedat will according to actual requirement. In addition to the complexelectric signals shown in FIG. 5B, another complex electric signals canbe used for driving the first and the second vibration structures 211,and 212, as those shown in FIG. 5B, in which the low-frequency signalsin the complex electric signals are of the same phase, but the phases ofthe high-frequency signals in the complex electric signals are oppositeto each other.

In FIG. 1, the first vibration structure 211 is driven by a firstdriving signal 90 so as to generate a first complex wave formed by afirst and a second wave signals while the second vibration structure 212is driven by a second driving signal 91 so as to generate a secondcomplex wave formed by a third and a fourth wave signals. In thisembodiment, the first and the second driving signals 90, and 91 are thetwo shown in FIG. 5A, so that the first and the third wave signals arehigh-frequency modes while the second and the fourth wave signals arelow-frequency modes, and thus, the first and the third wave signals areformed with a same first frequency and with the same phase while thesecond and the fourth wave signals are formed with a same secondfrequency but with opposite phases. Consequently, by the driving of thecomplex electric signals 90, and 91 of FIG. 5A, the first and the secondcomplex waves will actuate the substrate for enabling the swinging frame201 to rotate about a first axis, i.e. a rotation about the slow axis,while enabling the reflection mirror 204 to rotate about a second axis,i.e. a rotation about the fast axis. It is noted that the respectivefirst frequency of the first and the third wave signals are larger than15 KHz, and the respective second frequency of the second and the fourthwave signals are smaller than 1.5 KHz, but are not limited thereby. Inanother words, although the first frequency of the foregoing embodimentis higher than the second frequency, alternatively, the first frequencyis capable of being lower than the second frequency.

On the other hand, in the foregoing embodiment, the first wave signaland the third wave signal are formed with the same phase while thesecond wave signal and the fourth wave signal are formed with oppositephase; however, it is noted that, in alternative embodiment, the firstwave signal and the third wave signal are capable of being formed withopposite phase while the second wave signal and the fourth wave signalare formed with the same phase, which is clearly illustrated as FIG. 5B.Meanwhile, the first wave signal and the third wave signal are capableof being formed with a phase difference. In another embodiment, thesecond wave signal and the fourth wave signal are capable of beingformed with a phase difference.

The following description relates to how the swinging frame andreflection mirror are to be driven to rotate in the present disclosurethat is illustrated by defining the first and the third wave signals arehigh-frequency modes while the second and the fourth wave signals arelow-frequency modes, and thus the driving signals are similarly to thoseshown in FIG. 5A. As shown in FIG. 6A, when the second and the fourthwave signals containing in the vibrations of the first and the secondvibration structures 211, 212 are transmitted to the substrate 20 thatare opposite to each other in phase, the portions of the substrate 20that are coupled respectively to the first and the second vibrationstructures 211, 212 that are separated by the first slot 206 will bedriven to pivotally oscillating relative to each other in oppositephases, which will cause the fist axis 202 to twist, and consequently,drive the swinging frame 201 corresponding to the first axis 201 torotate, that is, the rotation of slow axis in the present disclosure. Itis noted that when the swinging frame 201 is at its resonant frequency,a larger rotation angle can be achieved.

Accordingly, the twist of the second axis 205 is enabled by thecontribution of the high-frequency first and the third wave signalscontaining in the vibrations of the first and the second vibrationstructures 211, 212. As shown in FIG. 6B, when the high-frequencyvibrations are transmitted to the second axis 205, the second axis 206will be caused to twist and thus driven the reflection mirror 204corresponding to the second axis 205 to rotate, that is, the rotation offast axis in the present disclosure. Similarly, when the reflectionmirror 204 is at its resonant frequency, a larger rotation angle can beachieved. By the vibrations of the first and the second vibrationstructures 211, 212, the twists of the first axis 202 and the secondaxis 205 can be controlled and consequently, the angles of the swingingframe 201 and the reflection mirror 204 are adjusted accordingly so asto achieve a specific scanning operation. It is noted that although thefix axis 202 and the second axis 205 in both the embodiments of FIG. 6Aand FIG. 6B are driven to rotate independently, they can be driven torotate simultaneously, but in a manner that the size of their respectiverotation angles as well as the angular difference between the swingingframe 201 and the reflection mirrors 204 are dependent upon theirrespective complex driving signals with respect to the compositions ofthe high-frequency modes and the low-frequency modes.

Please refer to FIG. 7A and FIG. 7B, which is a schematic diagramshowing a vibration-actuated micro mirror device according to a fourthembodiment of the present disclosure. The vibration-actuated micromirror device shown in the fourth embodiment is basically the same asthe one shown in FIG. 1, but is different in that: the vibration part 25is composed of a first vibration structure 250 and a second vibrationstructure 251 in a manner that the first and the second vibrationstructures 250, 251 are mounted directly and respectively on a firstarea 207 and a second area 208 that are formed at two opposite sides ofa first slot 206. Thus, there is no fixing plate being used in theembodiment of FIG. 7A. Moreover, the first and the second vibrationstructures 211, 212 are configured to share a same grounding electrode22, by that the amount of signal lines required can be reduced.Similarly, the first and the second vibration structures 211, 212 arealso being driven to vibrate by the use of complex electric signals thatare of the same phase in their respective high-frequency modes, but inopposite phase in their respective low-frequency modes, which is thesame as the description for the first embodiment and thus will not bedescribed further herein.

Although the first vibration structure 250, the second vibrationstructure 250 and the substrate 20 are independent components that arenot integrally formed in the embodiment shown in FIG. 7A. However, theycan be integrally formed as the one shown in FIG. 7B. In addition, thevibration-actuated micro mirror device shown in FIG. 7B is basically thesame as the one shown in FIG. 7A, but is different in that: the firstaxis 202 and the second axis 205 in FIG. 7B are configured differentlyfrom those of FIG. 7A. Moreover, the first and the second vibrationstructures 211, 212 in the embodiment of FIG. 7B are being driven tovibrate by the use of complex electric signals different form those ofthe embodiment shown in FIG. 7A, which are of the same phase in theirrespective low-frequency modes, but in opposite phase in theirrespective high-frequency modes.

With respect to the above description then, it is to be realized thatthe optimum dimensional relationships for the parts of the disclosure,to include variations in size, materials, shape, form, function andmanner of operation, assembly and use, are deemed readily apparent andobvious to one skilled in the art, and all equivalent relationships tothose illustrated in the drawings and described in the specification areintended to be encompassed by the present disclosure.

1. A vibration-actuated micro mirror device, comprising: a substrate,configured with a swinging frame and a reflection mirror while beingformed with a slot; and a vibration part, configured with a firstvibration structure and a second vibration structure in a manner thatthe first and the second vibration structures are disposed on thesubstrate respectively at two sides of the slot; wherein, the firstvibration structure has ability to receive a first driving signal so asto generate a first complex wave formed by a first wave signal and asecond wave signal; and the second vibration structure has ability toreceive a second driving signal to generate a second complex wave formedby a third wave signal and a fourth wave signal; wherein, the first wavesignal and the third wave signal are formed with a same first frequencywhile the second wave signal and the fourth wave signal are formed witha same second frequency, and the first and the second complex wavesactuate the substrate for enabling the swinging frame to rotate about afirst axis while enabling the reflection mirror to rotate about a secondaxis.
 2. The vibration-actuated micro mirror device of claim 1, whereinthe first frequency is higher than the second frequency.
 3. Thevibration-actuated micro mirror device of claim 1, wherein the firstfrequency is lower than the second frequency.
 4. The vibration-actuatedmicro mirror device of claim 1, wherein the first wave signal and thethird wave signal are formed with the same phase while the second wavesignal and the fourth wave signal are formed with opposite phase.
 5. Thevibration-actuated micro mirror device of claim 1, wherein the firstwave signal and the third wave signal are formed with opposite phasewhile the second wave signal and the fourth wave signal are formed withthe same phase.
 6. The vibration-actuated micro mirror device of claim1, wherein the first wave signal and the third wave signal are formedwith a phase difference.
 7. The vibration-actuated micro mirror deviceof claim 1, wherein the second wave signal and the fourth wave signalare formed with a phase difference.
 8. The vibration-actuated micromirror device of claim 1, wherein the substrate is formed with a firstopening while enabling a first axis, being a shaft formed on theswinging frame while protruding out from two opposite sides of theswinging frame by two first ends, to connected to two opposite innersides of the first opening respectively by the two first ends, and theswinging frame is further formed with a second opening while enabling asecond axis, being a shaft formed on the reflection mirror whileprotruding out from two opposite sides of the reflection mirror by twosecond ends, to connected to two opposite inner sides of the secondopening respectively by the two second ends.
 9. The vibration-actuatedmicro mirror device of claim 8, wherein the second axis is configured ina manner selected from the group consisting of: the second axis isaligned passing through the center of the reflection mirror, and thesecond axis is aligned a distance away from the center of the reflectionmirror.
 10. The vibration-actuated micro mirror device of claim 1,wherein the first and the second vibration structures are made of apiezoelectric material.
 11. The vibration-actuated micro mirror deviceof claim 1, wherein the first and the second vibration structures areconfigured to share a same grounding electrode.
 12. Thevibration-actuated micro mirror device of claim 1, wherein therespective first frequency of the first and the third wave signals arelarger than 15 KHz.
 13. The vibration-actuated micro mirror device ofclaim 1, wherein the respective second frequency of the second and thefourth wave signals are smaller than 1.5 KHz.
 14. The vibration-actuatedmicro mirror device of claim 1, wherein the first vibration structure isintegrally formed with the second vibration structure.